se >>> the fbi is leading the investigation. the attack is being treated asi an act of terrorism.teoris a federal source confirms to fox news that a suddeny national inn the u.s. on a student visa isis being questioned but so far is not classified as a suspect. more than 140 people were injured, 17 of them critically. >> the secrecy service expanned its perimeter in and around the white house following the boston marathon explosions. there's been no direct threat.a. pennsylvania avenue was sealed off at the white house. hous the closest people can get lafayette park. park. the extra personnel can be seenn on both the ground and the roofr of the white house. hous >>> while today is emancipationi day, the parade recognizing that d.c. holiday will go on scheduled. >> it will begin at 7:00 a.m. and mayor vincent gray, and police chief kathy lanier say sy that extra police measures arecs already in place. plac >> we leave that we are well prepared to defend the 632,000 0 people that live here and theand many thousands of people who v